1. Field of the Invention
The present invention relates to a porous electrode active material and a secondary battery including the same.
2. Description of the Related Art
Lithium secondary batteries recently have received most attention due to their high energy density and long lifetime. Typically, a lithium secondary battery includes an anode formed of a carbon material or lithium metal alloy, a cathode formed of lithium metal oxide, and an electrolyte having a lithium salt dissolved in an organic solvent.
Lithium metal is initially used as an anode active material constituting an anode electrode of a lithium secondary battery. However, since lithium may have low reversibility and safety, a carbon material is currently mainly used as the anode active material of the lithium secondary battery. The carbon material may have capacity lower than that of metal, but the carbon material may have low changes in volume and excellent reversibility, and may be favorable in terms of price.
However, demand for high-capacity lithium secondary batteries has gradually increased as the use of lithium secondary batteries has been increased. Accordingly, a high-capacity electrode active material capable of substituting the carbon material having low capacity is required. For this purpose, research into using metal (metalloid) exhibiting charge and discharge capacity higher than that of the carbon material and electrochemically alloyable with lithium, e.g., silicon (Si) and tin (Sn), as an electrode active material has been conducted.
However, the metal (metalloid)-based electrode active material has high changes in volume accompanying charge and discharge of lithium and thus, cracks and pulverization may be generated. Therefore, capacity of the battery may rapidly decrease and cycle lifetime may decrease as charge and discharge cycles are performed.